Time Zone Converter

📖 About This Tool

Before the late 19th century, every town kept its own local time based on the sun. This worked fine when travel was slow, but the railways changed that - a train crossing England would pass through dozens of local times, making timetables impossible to construct. In 1847, British railway companies adopted Greenwich Mean Time as a standard, and in 1884 the International Meridian Conference in Washington divided the world into 24 hourly zones, each 15 degrees of longitude wide, all referenced to the Greenwich meridian.

Daylight Saving Time adds another layer of complexity. First proposed seriously by New Zealand entomologist George Hudson in 1895 (so he would have more daylight for collecting insects after work), it was adopted widely during the First World War to conserve coal. Not all countries observe it, and those that do start and end on different dates. This tool uses your browser's built-in timezone database, which is maintained by the IANA and updated whenever governments change their rules - so the conversions shown are always current.

How to Use

• • Set a date and time in the input field (defaults to right now), or tap "Current Time" to reset.
• • Use the city search to add up to 5 cities to compare simultaneously.
• • Cards highlighted in green indicate it is currently business hours (9am-5pm) in that city.
• • Blue or red labels show if the date is the next day or previous day relative to your input time.

Understanding UTC Offsets